., president obama addresses the country vowing to find those responsible. >> make no mistake, we will get to the bottom of this. any responsible individuals, any responsible groups will feel the full weight of justice. >> no matter how many times you see it it is still just as terrifying. i do want to show one photograph, as well, speaking to what was not the hundreds and hundreds of bags waiting for runners who were never able to claim them again, a snapshot of innocence and perfection on that patriots' day suspended if not lost. george. >> josh, the runners across the finish line right before the moment of impact, bill iffrig is right here, 78-year-old bill i have africa, rebecca roche and we have seen that image. i want to put it up on the screen as you were just approaching the finish line, the blast hit and you went down right there. tell us what you remember. >> yeah, i didn't know what had happened. all of a sudden this enormous blast right next to me and it just kind of buckled my legs and i knew i was going down so i hit the blacktop, i started looking around to see how we we